This invention relates generally to cosmetic preparations and more particularly to the use of nanoscale chitosans and/or chitosan derivatives in deodorizing preparations.
In the field of personal care, deodorants are used to eliminate unpleasant body odors. Typical examples of such substances are aluminium compounds, such as aluminium sulfate or aluminium chlorohydrate, zinc salts and citric acid compounds. Since the problem of odor inhibition has by no means been completely solved, there is still a need for new preparations which contain dermatologically compatible deodorants with a long-lasting effect.
It is known from DE 19540296C2 that chitosans inhibit the activity of esterase-producing bacteria and that a synergistic deodorizing effect is obtained together with esterase inhibitors and aluminium chlorohydrates. The chitosans have a bacteriostatic effect, i.e. the population of the particular germs is controlled but not killed off in order not to impair the biological equilibrium of the skin flora. The effect of the chitosans or chitosan derivatives and its duration are always associated with the rate at which the compounds are incorporated and absorbed. So far as the compounds hitherto available are concerned, there is considerable potential for improvement in this regard.
The general use of water-soluble chitosan salts in deodorants and antibacterial cosmetics is claimed in Japanese patent application JP 63290808. However, there is a need to further improve the antibacterial activity of chitosans by special formulations.
“Nanonized material” in the context of the present invention is understood to mean spherical aggregates with a diameter of about 1 to about 500 nm which contain at least one solid or liquid core surrounded by at least one continuous membrane. Their use in cosmetics was described in 1997 by Zülli, F. and Suter, F. (Preparation and Properties of Small Nanoparticles for Skin and Hair Care, Seifen-Öle-Fette-Wachse 123 (1997), No. 13, p. 880, 883-885) and by Mehnert, W. et al. (Solid Lipid Nanoparticles, A Novel Carrier for Cosmetics and Pharmaceuticals, Pharm. Ind. 59 (1997), pp. 511-514). The core and membrane may consist of one and the same material or even of different materials.
The processing of auxiliaries and active substances in selected formulations can be simplified by using them in the form of nanoparticles. This applies above all where there is incompatibility with other auxiliaries. In addition, the release and absorption of substances can be controlled through the particle or capsule size, by the use of various auxiliaries or various physicochemical properties.
U.S. Pat. Nos. 5,194,262 and 5,271,934 describe microcapsules containing antiperspirants. These microcapsules acquire bioadhesive properties through constituents of the membrane or even additional coatings and thus contribute to a long-lasting effect.
Accordingly, the problem addressed by the invention was to improve the distribution and uptake of chitosans or chitosan derivatives and at the same time to obtain a long-lasting deodorizing effect. In addition, the biopolymers would lend themselves to simple incorporation in the formulation and their compatibility with anionic auxiliaries would be improved. The final formulation would be distinguished by a pleasant skin feel, high dermatological compatibility and high stability.